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arXiv · 1605.02863

Generating Random Earthquake Events for PTHA

Randall J. LeVeque·Knut Waagan·Frank I. González·Donsub Rim·Guang Lin
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Abstract

In order to perform probabilistic tsunami hazard assessment (PTHA) based on subduction zone earthquakes, it is necessary to start with a catalog of possible future events along with the annual probability of occurance, or a probability distribution of such events that can be easily sampled. For nearfield events, the distribution of slip on the fault can have a significant effect on the resulting tsunami. We present an approach to defining a probability distribution based on subdividing the fault geometry into many subfaults and prescribing a desired covariance matrix relating slip on one subfault to slip on any other subfault. The eigenvalues and eigenvectors of this matrix are then used to define a Karhunen-Lo\`eve expansion for random slip patterns. This is similar to a spectral representation of random slip based on Fourier series but conforms to a general fault geometry. We show that only a few terms in this series are needed to represent the features of the slip distribution that are most important in tsunami generation, first with a simple one-dimensional example where slip varies only in the down-dip direction and then on a portion of the Cascadia Subduction Zone.

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Randall J. LeVeque, Knut Waagan, Frank I. González, Donsub Rim, Guang Lin. 2016-05-10. Generating Random Earthquake Events for PTHA. https://doi.org/10.1137/17m1113679

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